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The amnion does not produce hormones; hormone production to maintain pregnancy is primarily by the trophoblast and placenta, including human chorionic gonadotropin and progesterone.

Nutrient exchange occurs at the placenta via chorionic villi, not the amnion, which acts as a barrier and container for amniotic fluid but does not participate in exchange functions.

The umbilical cord develops from the connecting stalk and allantois, not from the amnion. The amnion lines the amniotic cavity but does not differentiate into the umbilical cord.

Fusion of the male and female pronuclei marks syngamy, which is the final step of fertilization after the sperm has already entered the oocyte. This event occurs after both the acrosomal and cortical reactions and does not define the acrosomal reaction itself.

A rapid depolarization of the oocyte membrane is part of the “fast block to polyspermy,” which is associated with the cortical reaction, not the acrosomal reaction. This block prevents multiple sperm from fertilizing the oocyte after one sperm has succeeded, but it happens after the acrosomal reaction is complete.

Migration of sperm through the cervical mucus and uterus is a part of sperm transport and capacitation, which occur prior to the acrosomal reaction. This is necessary for the sperm to even reach the site of fertilization, but it is not the defining event of the acrosomal reaction.

The chorion laeve, or smooth chorion, forms from villi on the side of the chorion away from the decidua basalis; these villi regress and become avascular, so it does not contribute to placental formation.

The yolk sac is an early embryonic structure involved in initial hematopoiesis and nutrient transfer but is not formed from chorionic villi and is distinct from the chorion.

The umbilical cord develops from the connecting stalk and contains blood vessels connecting fetus to placenta but is not formed by chorionic villi proliferation adjacent to the decidua basalis.

Diffusion of fluid from maternal blood across the placental membranes contributes minimally to amniotic fluid volume, especially in the third trimester, as fetal urine becomes predominant.

Secretions from the fetal gastrointestinal tract do not contribute significantly to amniotic fluid volume; rather, swallowed amniotic fluid is absorbed, not secreted into the cavity.

Transudation from fetal skin is significant only early in gestation before keratinization, which is complete by about 20 weeks, greatly reducing this source by the third trimester.

The formation of a blastocyst, containing an inner cell mass and trophoblast, occurs several days post-fertilization during the blastocyst stage, not immediately upon sperm-oocyte fusion.

Differentiation of the morula into an embryo occurs after several rounds of cleavage and compaction, occurring days after fertilization, thus not at the immediate completion of fertilization.

Rapid mitotic divisions producing blastomeres begin after fertilization but represent cleavage stages rather than the completion event of fertilization itself, which is specifically defined by pronuclear fusion.

One artery and one vein represent an abnormal finding known as a single umbilical artery, which may be associated with congenital anomalies or fetal growth restriction and is not the normal anatomy.

Two veins and one artery is not a typical umbilical cord configuration; the umbilical cord normally has only one vein.

Three arteries and no veins is anatomically incorrect and incompatible with fetal survival due to lack of oxygenated blood return.

Large molecular weight and high protein binding reduce placental crossing. Large molecules (>1000 daltons) cannot easily cross, and high protein binding limits free drug available for transfer.

Ionized drugs at physiological pH are less lipid-soluble and cross the placenta poorly due to reduced membrane permeability.

Water-soluble and high molecular weight drugs have limited placental transfer because they cannot readily diffuse across the lipid membranes.

Macrosomia, defined as fetal weight above 4000 grams, is unrelated to oligohydramnios and more often linked to maternal diabetes or genetic factors. Reduced amniotic fluid does not cause fetal overgrowth.

Shoulder dystocia is an obstetric complication caused by fetal size disproportion, often macrosomia, and is not directly caused by oligohydramnios.

Hyperbilirubinemia results from increased red blood cell breakdown or impaired conjugation, unrelated to amniotic fluid volume. Oligohydramnios does not predispose to bilirubin metabolism disorders.

Measuring fundal height is a non-invasive clinical method to estimate fetal growth and weight, unrelated to amniocentesis.

Doppler ultrasound assesses uteroplacental blood flow and fetal circulation but does not involve sampling amniotic fluid.

Fetal heart tones are detected by Doppler or fetoscope, especially in early pregnancy, and are not confirmed by amniocentesis.

Estrogen and luteinizing hormone are endocrine hormones involved in ovulation and endometrial preparation but do not directly mediate cellular adhesion during blastocyst attachment.

Fibrin and collagen are extracellular matrix components but are not the primary molecules facilitating blastocyst adhesion; rather, they form structural scaffolds.

Histamine and prostaglandins are involved in inflammatory responses and uterine contractions but do not mediate the adhesive interactions of the blastocyst.